The present invention relates to a fifth wheel coupling assembly, and in particular to a novel mounting and cross member assembly for coupling a fifth wheel hitch plate to an associated vehicle.
Fifth wheel coupling systems are used in wide variety of applications for coupling heavy duty trailers to associated tractors, as well as for coupling recreational vehicles with associated towing vehicles. FIG. 1 illustrates a typical prior construction of a tractor frame and a fifth wheel mounting system 10 for tractor/trailer applications. As illustrated, the tractor frame and mounting system 10 includes a pair of parallel frame rails 12 spaced apart and that support a suspension 14, a drive train (not shown) and a fifth wheel coupling apparatus 16 for connecting a trailer to the tractor. While the frame rails 12 are illustrated as ending under a deck 17 it should be noted that the rails 12 continue forwardly of the deck 17 and extend under a cab of the tractor and support the cab and an engine of the tractor.
The coupling apparatus 16 includes a fifth wheel hitch 20 and a mounting bracket and base plate assembly 18 configured to connect the fifth wheel hitch 20 to the frame rails 12. The mounting bracket and base plate assembly 18 includes a pair of brackets 22 connected to ends of a base plate 24. The base plate 24 is constructed of a planar sheet of steel that includes a pair of mounting brackets 26 extending upwardly from a top surface of the base plate 24. As illustrated, the mounting brackets 26 are fixedly welded to the base plate 24, while the base plate 24 is fixedly welded to the brackets 22. The coupling apparatus 16 is connected to the frame rails 12 by placing ends of the base plate 24 over the top surface of the frame rails 12 and by inserting fasteners (not shown) through the brackets 22 and into the frame rails 12. Therefore, the brackets 22 assist in connecting the coupling apparatus 16 to the frame rails 12 of the tractor. Each mounting bracket 26 of the mounting bracket and the base plate assembly 18 includes an elongated aperture 28 therein configured to accept conventional attachment structure (not shown) for connecting the fifth wheel hitch 20 to the base plate 24.
The fifth wheel hitch 20 is configured to accept a pin of a tractor trailer to connect the trailer to the tractor. Since the fifth wheel hitch 20 accepts the pin within a center opening 30, the primary load of the trailer rests on the top surface of the fifth wheel hitch 20. As a result, the primary load of the trailer is on the mounting bracket and the base plate 24 at the center of the base plate 24. The load from the trailer is transferred to the attachment points of the mounting bracket and base plate assembly 18 to the frame rails 12 through heavy ribs and other structure that act as a beam.
As illustrated, the fifth wheel hitch 20 (FIG. 2) includes a hitch plate 11 defining the throat 30 for receiving a kingpin (not shown). The hitch plate 11 has a bottom face 15, back ribs 27 that extend from the bottom base 15, a peripheral flange 19 that extends from a periphery of the bottom face 15 and is connected to ends of the back ribs 27, and a main rib 21 that extends from the bottom face 15 between the back ribs 27 and a portion of the peripheral flange 19, with the main rib 21 being connected at ends 23 to the peripheral flange 19. A pair of skirts 29 extend from the hitch plate 11 adjacent the back rib 27 and define a tapered mouth leading to the throat 30. A pair of skirt ribs 33 are positioned on the skirts 29. A mounting rib 35 is located inwardly of the peripheral flange 19 on each side of the throat 30. The mounting brackets 26 are connected to the fifth wheel hitch 20 by inserting the mounting brackets into a space 37 between the mounting rib 35 and the peripheral flange 19. A mounting pin (not shown) is inserted through the aligned apertures in the peripheral flange 19 and the mounting rib 13 to connect the fifth wheel hitch 20 to the mounting brackets 26 and the associated tractor.
The prior construction of the tractor frame and fifth wheel mounting system 10, as detailed above, requires a welded connection between the mounting brackets 26 and the base plate 24 as well as a welded connection between the base plate 24 and the brackets 22, thereby adding to the constructions costs associated with the assembly of the mounting system.
Further, the structural rigidity as provided by the base plate 24 extending between the mounting brackets 26 remains relatively constant as the base plate 24 extends entirely under the mounting brackets 26. Moreover, the prior constructions of the tractor frame and fifth wheel mounting systems allow forces developed during operation of the associated vehicle to degrade ride and control characteristics. Specifically, as illustrated in FIGS. 3–6, forces exerted on the vehicle frame may cause misalignment and/or deformation of the frame, including “racking” (FIG. 3), “bowing out” (FIG. 4), “bowing in” (FIG. 5), and “twisting” (FIG. 6).
Accordingly, a fifth wheel and mounting assembly providing decreased construction and assembly costs, while simultaneously providing a variable and dynamic structural rigidity is desired.